Field
The present disclosure relates generally to wireless communication systems and, more specifically, to a compound semiconductor field effect transistor including a self-aligned gate.
Background
A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may include a radio frequency (RF) transceiver to transmit and receive data for two-way communication. A mobile RF transceiver may include a transmit section for data transmission and a receive section for data reception. For data transmission, the transmit section may modulate an RF carrier signal with data to obtain a modulated RF signal, amplify the modulated RF signal to obtain an amplified RF signal having the proper output power level, and transmit the amplified RF signal via an antenna to a base station. For data reception, the receive section may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the base station.
The transmit section of the mobile RF transceiver may amplify and transmit a communication signal. The transmit section may include one or more circuits for amplifying and transmitting the communication signal. The amplifier circuits may include one or more amplifier stages that may have one or more driver stages and one or more power amplifier stages. Each of the amplifier stages includes one or more transistors configured in various ways to amplify the communication signal. The transistors configured to amplify the communication signal are generally selected to operate at substantially higher frequencies for supporting communication enhancements, such as carrier aggregation. These transistors are commonly implemented using compound semiconductor transistors, such as bipolar junction transistors (BJTs), heterojunction bipolar transistors (HBTs), high-electron-mobility transistors (HEMTs), pseudomorphic high-electron-mobility transistors (pHEMTs), and the like.
Design challenges for mobile RF transceivers include performance considerations for meeting future 5G and 5G+ transmission frequency specifications. These future 5G/5G+ performance specifications mandate a ten-fold transmission frequency increase (e.g., 28 gigahertz (GHz) to 60 GHz) over current standards for supporting future transmission frequency specifications. High-electron-mobility transistors may improve upon heterojunction transistors by supporting substantially higher transmission frequencies.
High-electron-mobility transistors are excellent candidates for meeting future 5G/5G+ transmission frequency specifications. Unfortunately, current compound semiconductor (e.g., gallium nitride GaN) transistors, which are mostly used in base stations, have too high of an operating voltage to be useful in mobile devices. GaAs (gallium arsenide) pseudomorphic high-electron-mobility transistors have a lower power density, which make them a poor candidate for implementing power amplifiers of mobile devices (e.g., smartphones) that support 5G/5G+ transmission frequency specifications.